Fábio Carvalho

Abstract:

The diagnosis of hydrological flow and rain interception by vegetation is justified by the need to know the influence of these elements in watersheds, since vegetation and proper land use are responsible for maintaining the quality of the slopes, avoiding erosion, soil loss, siltation of watercourses and induces maintenance of groundwater reserves. This work was a pilot study that obtained data from the components of the hydrological system of the Queixada Stream (MHQ) tributary of the Rio Claro tributary, represented in the SE-22 letter from Jataí (GO), in the quadrant comprised by the coordinates UTM: E 419124.99 m, N 8028060.83 m, E 423105.19 m and N 8021056.99 m. MHQ was mapped in its land use and occupation aspects through satellite imagery from the 2007/2008 years (Google Earth) and through a panchromatic vertical aerial photograph from 1965 (US Air Force - USAF). Specific equipment was installed in a slope forest of MHQ for the collection of total precipitation, internal precipitation and effective precipitation data, obtaining the data of rain interception by vegetation and the initial abstraction. Rain gauges were installed at predefined MHQ points to collect total rainfall data. The flow rate at the mouth of the MHQ main course was measured monthly to obtain the average flow data. The necessary data for the evapotranspiration calculations were obtained from the National Institute of Meteorology (INMET) Jataí Meteorological Station. Real evapotranspiration (ETR) was obtained through the Penman equation (TUCCI; BELTRAME, 2009). Groundwater recharge and runoff for land uses of 2007/2008 and 1965 were determined using the method of Palmer (1965) apud Alley (1984). Water storage (S) was determined by the CN (curve number - Soil Conservation Service “SCS”) method, using the following CN values ​​for the considered uses: capoeira - 71; gravel pit - 86; tillage - 71; kill - 70; pasture - 70; urban - 90. Data were manipulated using Excel and Surfer software. It was verified that the rainfall partitions (internal precipitation, effective precipitation, interception and initial abstraction) presented differences in the analysis of variance from seasonality and, consequently, by the volumes, rainfall intensities and phytophysiognomy analyzed. It was evidenced that the largest surface runoff occurred in more waterproofed areas, which was the urban one, where the lowest relative groundwater recharge rates occurred. The smallest defluvia and the highest recharge rates were in the forest, capoeira and pasture areas. The results showed that the basin lost 73,963,427 m³ of water storage capacity in land use in 1965 compared to the use presented in 2007/2008. It can be concluded that measures are needed to preserve the recharge areas, because with the advancement of the urban sludge it may increase the surface runoff, reducing the recharge of groundwater, causing the reduction of the piezometric level, the silting of the courses. water, erosive processes, the death of springs and streams, affecting the entire ecosystem. The preservation of the Queixada Forest must be maintained, the urban expansion restricted and the rural area must obey the determinations of the Brazilian environmental legislation.

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